Roger Stewarts Extreme Calf Machine. Developed by Roger Stewart the Extreme Calf Machine helps build bigger and stronger calves and is very affordable for anyone to own. Roger Stewart's Extreme Calf Machine is built heavy duty for gyms but is portable and perfect for home gyms, rehab, athletes, and personal trainers as well. If you are looking for a calf building solution the Roger Stewart Extreme Calf Machine is the answer to your calf problems. Lifetime Warranty. Patent number D460,507